Calcium oxide or “quicklime” is a known expansive agent and heat-release agent used in cements and concretes. The hydration reaction of calcium oxide is rapid, highly exothermic, difficult to control, such that its applications are limited due to a drastic and intense hydration profile. The hydration reaction of calcium oxide can be considerably attenuated by calcination processing, e.g., U.S. Pat. No. 4,354,877 of Kawano et al., whereby burning of the calcium oxide is done at very high temperatures around 1400° C. The manufacturing of hard-burned quicklime is difficult; and few products appear to be commercially available.
In U.S. Pat. No. 4,565,579, Fujioka et al. taught combining calcium fluoride with calcium oxide and hydration retarding agents, and heating this composition to a temperature of from about 800° C.-1400° C. This chemical composition is intended for “gently” breaking rocks or concrete masses apart.
While one might find calcium oxide listed as an expansive agent for use in concrete and other cementitious materials, it is not surprising to find other expansion agents, such as magnesium oxide or calcium sulfoaluminate, as more preferred due to their less intensive hydration profiles. See e.g., U.S. Pat. No. 8,277,556 of Neal S. Berke et al. (owned by the common assignee hereof), at column 11, lines 56-59.
With regard to cement compositions containing quicklime, it is known to use common retarders (e.g., derivatives of carboxylic acid, hydroxyl acid, ketocarboxylic acid, sugars, sugar alcohol) for postponing the hydration reaction (coagulation and hardening) of the cement to a time that is subsequent to the hydration reaction of the quicklime, See e.g., Japanese Publication No. 200236364. However, as will be demonstrated by the present inventor hereinafter, the use of conventional retarders attenuates the overall exothermic profile of calcium oxide hydration, without achieving control over onset of hydration (e.g., reaction initiation).
The present inventor believes that a novel composition and method for controlling the hydration induction of calcium oxide is needed.